Interspinous spacer

ABSTRACT

An implantable spacer&#39;for placement between adjacent spinous processes in a spinal motion segment is provided. The spacer includes a body defining a longitudinal passageway. A first arm and a second arm are connected to the body. Each arm has a pair of extensions and a saddle defining a receiving portion configured for seating a spinous process of a scoliotic spine or a spine with misaligned spinous processes. Each arm has a proximal miming surface and is capable of rotation with respect to the body. An actuator assembly is disposed inside the longitudinal passageway and connected to the body. When advanced, a threaded shaft of the actuator assembly contacts the caming surfaces of arms to rotate them from an undeployed configuration to a deployed configuration. In the deployed configuration, the distracted adjacent spinous processes are seated in the superior and inferior arms of the spacer. Variations adapted for scoliotic curves are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of and is acontinuation-in-part of U.S. Provisional Patent Application Ser. No.61/011,199 entitled “Interspinous spacer” filed on Jan. 15, 2008 whichis incorporated herein by reference in its entirety. This applicationalso claims priority to and is a continuation-in-part of U.S. patentapplication Ser. No. 12/338,793 entitled “Spacer insertion instrument”filed on Dec. 18, 2008 which is a non-provisional of U.S. ProvisionalPatent Application Ser. No. 61/008,418 entitled “Spacer insertioninstrument” filed on Dec. 19, 2007 which is incorporated herein byreference in its entirety. This application also claims priority to andis a continuation-in-part of U.S. patent application Ser. No. 12/205,511entitled “Interspinous spacer” filed on Sep. 5, 2008 which is anon-provisional of U.S. Provisional Patent Application Ser. No.60/967,805 entitled “Interspinous spacer” filed on Sep. 7, 2007 and acontinuation-in-part of U.S. patent application Ser. No. 12/220,427entitled “Interspinous spacer” filed on Jul. 24, 2008 which is anon-provisional of U.S. Provisional Patent Application Ser. No.60/961,741 entitled “Insterspinous spacer” filed on Jul. 24, 2007 and isa continuation-in-part of U.S. patent application Ser. No. 12/217,662entitled “Interspinous spacer” filed on Jul. 8, 2008 which is anon-provisional of U.S. Provisional Patent Application No. 60/958,876entitled “Interspinous spacer” filed on Jul. 9, 2007 and acontinuation-in-part of U.S. patent application Ser. No. 12/148,104entitled “Interspinous spacer” filed on Apr. 16, 2008 which is anon-provisional of U.S. Provisional Patent Application Ser. No.60/923,971 entitled “Interspinous spacer” filed on Apr. 17, 2007 andU.S. Provisional Patent Application Ser. No. 60/923,841 entitled “Spacerinsertion instrument” filed on Apr. 16, 2007, all of which are herebyincorporated by reference in their entireties. This application is alsoa continuation-in-part of U.S. patent application Ser. No. 11/593,995entitled “Systems and methods for posterior dynamic stabilization of thespine” filed on Nov. 7, 2006 and a continuation-in-part of U.S. patentapplication Ser. No. 11/582,874 entitled “Minimally invasive tooling fordelivery of interspinous spacer” filed on Oct. 18, 2006 and acontinuation-in-part of U.S. patent application Ser. No. 11/314,712entitled “Systems and methods for posterior dynamic stabilization of thespine” filed on Dec. 20, 2005 and a continuation-in-part of U.S. patentapplication Ser. No. 11/190,496 entitled “Systems and methods forposterior dynamic stabilization of the spine” filed on Jul. 26, 2005 anda continuation-in-part of U.S. patent application Ser. No. 11/079,006entitled “Systems and methods for posterior dynamic stabilization of thespine” filed on Mar. 10, 2005 which is a continuation-in-part of U.S.patent application Ser. No. 11/052,002 entitled “Systems and methods forposterior dynamic stabilization of the spine” filed on Feb. 4, 2005which is a continuation-in-part of U.S. patent application Ser. No.11/006,502 entitled “Systems and methods for posterior dynamicstabilization of the spine” filed on Dec. 6, 2004 which is acontinuation-in-part of U.S. patent application Ser. No. 10/970,843entitled “Systems and methods for posterior dynamic stabilization of thespine” filed on Oct. 20, 2004, all of which are hereby incorporated byreference in their entireties.

BACKGROUND

With spinal stenosis, the spinal canal narrows and pinches the spinalcord and nerves, causing pain in the back and legs. Typically, with age,a person's ligaments may thicken, intervertebral discs may deteriorateand facet joints may break down—all contributing to the condition of thespine characterized by a narrowing of the spinal canal. Injury,heredity, arthritis, changes in blood flow and other causes may alsocontribute to spinal stenosis.

Doctors have been at the forefront with various treatments of the spineincluding medications, surgical techniques and implantable devices thatalleviate and substantially reduce debilitating pain associated with theback. In one surgical technique, a spacer is implanted between adjacentspinous processes of a patient's spine. The implanted spacer opens theforamen and spinal canal, maintains the desired distance betweenvertebral body segments, and as a result, avoids impingement of nervesand relieves pain. For suitable candidates, an implantable interspinousspacer may provide significant benefits in terms of pain relief.However, there is a need for an implantable interpsinous spacer forpatients with adjacent spinous processes that are not aligned such as inpatients suffering with scoliosis. Scoliosis is the lateral or sidewayscurvature caused by congenital, neuromuscular, idiopathic, syndromic orpostural conditions. An example of a scoliotic spine is shown in FIG.12.

Any surgery is an ordeal. However, the type of device and how it isimplanted has an impact. For example, one consideration when performingsurgery to implant an interspinous spacer is the size of the incisionthat is required to allow introduction of the device. Small incisionsand minimally invasive techniques are quick and generally preferred asthey affect less tissue and result in speedier recovery times. As such,there is a need for interspinous spacers that work well with surgicaltechniques that are minimally invasive for a patient with misalignedspinous processes such as patients with scoliosis. The present inventionsets forth such a spacer.

SUMMARY

According to one aspect of the invention, an implant configured forplacement between adjacent spinous processes in a spinal motion segmentwith a scoliotic curve and configured to laterally stabilize the spacerwith respect to said adjacent spinous processes is provided.

An implant for placement between adjacent spinous processes in a spinalmotion segment is provided. The implant includes a body defining alongitudinal passageway through at least a portion of the body. A firstarm connected to the body and capable of rotation with respect to thebody. The first arm has a first pair of extensions and a first bridgedefining a spinous process receiving portion for seating a first spinousprocess therein. The first arm has a first proximal canting surface. Theimplant further includes a second arm connected to the body and capableof rotation with respect to the body. The second arm has a second pairof extensions and a second bridge defining a spinous process receivingportion for seating a second spinous process therein. The second arm hasa second proximal earning surface. The implant further includes anactuator connected to the body. The actuator is configured such that theactuator is disposed inside the body and configured to move relative tothe body and contact the earning surfaces of the arms to rotate themfrom a first configuration in which the arms are substantially parallelto the longitudinal axis of the body to a second configuration in whichthe first arm seats the first spinous process and the second arm seatsthe second spinous process. At least one of the first arm and second aimis configured to seat the spinous processes of a spinal motion segmentwith a scoliotic curve.

An implant for placement between adjacent spinous processes in a spinalmotion segment is provided. The implant includes a body defining alongitudinal axis. A first arm is connected to the body and has a firstpair of extensions defining a spinous process receiving portion forseating a superior spinous process therein. The implant includes asecond arm connected to the body. The second arm has a second pair ofextensions defining a spinous process receiving portion for seating aninferior spinous process therein. One extension of the first pair andone extension of the second pair that are adjacent to each other on thesame side of the spacer are both shorter than the other of theextensions.

An implant for placement between adjacent spinous processes in a spinalmotion segment is provided. The implant includes a body defining alongitudinal axis. A first arm is connected to the body having a firstpair of extensions defining a spinous process receiving portion forseating a superior spinous process therein. A second aim is connected tothe body. The second arm has a second pair of extensions defining aspinous process receiving portion for seating an inferior spinousprocess therein. The distance between the first pair of extensions isgreater than the distance between the second pair of extensions toaccommodate a generally wider lower or caudal end of a superior spinousprocess relative to a generally narrower upper or cephalad end of aninferior spinous process.

An implant for placement between adjacent spinous processes in a spinalmotion segment is provided. The implant includes a body defining alongitudinal axis. A first arm is connected to the body and configuredto laterally stabilize the body with respect to a first spinous processwhen in a deployed configuration. A second arm is connected to the bodyand configured to laterally stabilize the body with respect to a secondspinous process when in a deployed configuration. The first and secondarms are configured for placement between adjacent spinous processes inwhich at least one of the adjacent spinous processes has a projection ina coronal plane that is angled with respect to the sagittal plane.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a perspective view of a spacer according to the presentinvention.

FIG. 1b is a side view of a spacer according to the present invention.

FIG. 1c is a top view of a spacer according to the present invention.

FIG. 1d is a cross-sectional view of a spacer taken along line A-A ofFIG. 1c according to the present invention.

FIG. 1e is an end view of a spacer according to the present invention.

FIG. 1f is an exploded view of a spacer according to the presentinvention.

FIG. 2a is a perspective view of a half of a body of a spacer accordingto the present invention.

FIG. 2b is a side view of half of a body of a spacer according to thepresent invention.

FIG. 2c is a perspective view of a half of a body of a spacer accordingto the present invention.

FIG. 2d is a side view of half of a body of a spacer according to thepresent invention.

FIG. 3a is a perspective view of a superior wing of a spacer accordingto the present invention.

FIG. 3b is a top view of a superior wing of a spacer according to thepresent invention.

FIG. 3c is a side view of a superior wing of a spacer according to thepresent invention.

FIG. 3d is a perspective view of an inferior wing of a spacer accordingto the present invention.

FIG. 3e is a bottom view of an inferior wing of a spacer according tothe present invention.

FIG. 3f is a side view of an inferior wing of a spacer according to thepresent invention.

FIG. 4a is a side view of a spacer according to the present invention.

FIG. 4b is a side view of a spacer with wings partially deployedaccording to the present invention.

FIG. 4c is a side view of a spacer with wings in a deployedconfiguration according to the present invention.

FIG. 4d is a side view of a spacer with wings in a deployed and extendedconfiguration according to the present invention.

FIG. 5a is a cross-sectional view of a spacer with wings in a partiallydeployed configuration according to the present invention.

FIG. 5b is a cross-sectional view of a spacer with wings in a deployedconfiguration according to the present invention.

FIG. 5c is a cross-sectional view of a spacer with wings in a deployedand extended configuration according to the present invention.

FIG. 6a is a semi-transparent view of a spacer with wings partiallydeployed according to the present invention.

FIG. 6b is a semi-transparent view of a spacer with wings in a deployedconfiguration according to the present invention.

FIG. 6c is a semi-transparent view of a spacer with wings in a deployedand extended configuration according to the present invention.

FIG. 7 is a partial cross-sectional view of a spacer according to thepresent invention located between two adjacent spinous processes.

FIG. 8 is a cross-sectional, view of a spacer according to the presentinvention located between two adjacent spinous processes.

FIG. 9 is a cross-sectional view of a spacer according to the presentinvention located between two adjacent spinous processes.

FIG. 10 is a partial view of a spacer according to the presentinvention.

FIG. 11 is a partial view of a spacer and driving tool according to thepresent invention.

FIG. 12 is a posterior view of part of a spine with a scoliotic curve.

FIG. 13a is a side view of a spacer connected to an insertion instrumentaccording to the present invention.

FIG. 13b is a side view of a spacer in a partially deployedconfiguration connected to an insertion instrument according to thepresent invention.

FIG. 13c is a side view of a spacer in a deployed configurationconnected to an insertion instrument according to the present invention.

FIG. 13d is a side view of a spacer in a deployed and extendedconfiguration connected to an insertion instrument according to thepresent invention.

FIG. 14 is a perspective view of a spacer in a deployed configurationaccording to the present invention implanted between adjacent spinousprocesses of two vertebral bodies.

DETAILED DESCRIPTION

With reference to FIGS. 1a -1 f, various views of a spacer 10 accordingto the present invention are shown. The spacer 10 includes a body 12, asuperior extension member, arm or wing 14, an inferior extension member,arm or wing 16, and an actuator assembly 18.

Turning now to FIGS. 2a -2 d, the body will now be described. The body12 is shown to have a clamshell construction with a left body piece 20(shown in FIGS. 2a and 2b ) joined to a right body piece 22 (shown inFIGS. 2c and 2d ) to capture arms 14, 16 inside. With the right and leftbody pieces 20, 22 joined together, the body 12 is generallycylindrical. The spacer body 12 has a cross-sectional size and shapethat allows for implantation between adjacent spinous processes andfacilitates delivery into a patient through a narrow port or cannula.

The inside of the body 12 defines an arm receiving portion 24 and anactuator assembly receiving portion 26 with features formed in each ofthe left and right body pieces 20, 22 that together define the arm andactuator assembly receiving portions 24, 26. In one variation, the armreceiving portion 24 includes slots 28 that receive pins formed on thearms 14, 16 such that the pins rotate and/or translate inside the slots28. The actuator assembly receiving portion 26 includes a threadedpassageway 30. Other features include a tongue and groove for matingwith the opposite clamshell.

The outside of the body 12 defines a ledge 32 along at least a portionof the periphery. Notches 34 are formed at opposite locations and areconfigured for pronged attachment to a spacer delivery instrument. Whenjoined together, the left and right body pieces 20, 22 define a proximalopening 36 (as also seen in FIG. 1e ) and a distal opening 38 (as alsoseen in FIG. 1a ) in the body 12. A longitudinal scallop (not shown)extending from the proximal end of the spacer to the distal end isformed to facilitate placement of the spacer 10 between and to conformto the anatomy of adjacent spinous processes. In one variation, twooppositely located longitudinal scallops are formed in the outer surfaceof the body 12 such that, when implanted in a patient's spine, onescallop faces the superior spinous process and the other scallop facesthe inferior spinous process. In one variation, the distance betweenoppositely located longitudinal scallops is approximately 8.0millimeters imparting the spacer 10 with a low profile advantageous forinsertion between closely spaced or “kissing” spinous processes.

Turning now to FIGS. 3a -3 c, the superior arm 14 is shown and in FIGS.3d -3 f, the inferior arm 16 is shown. The superior and inferior aims14, 16 include pins 40 for mating with the body 12, in particular, formating with the slots 28 of the arm receiving portion 24. Each of thesuperior and inferior aims 14, 16 includes at least one earning surface41, 43, respectively, for contact with the actuator assembly 18. Thesuperior and inferior arms 14, 16 include elongated superior extensions42 a, 42 b and elongated inferior extensions 44 a, 44 b, respectively.Extensions 42 a and 44 a are located on the left adjacent to the leftbody piece 20 and extensions 42 b and 44 b are located on right adjacentto the right body piece 22. Superior extensions 42 a, 42 b extendsubstantially parallel to each other in both an undeployed configurationand in a fully-deployed configuration as do inferior extensions 44 a, 44b. Extending between extensions 42 a, 42 b is a strut, bridge, bracketor saddle 46 that forms a superior substantially U-shaped configurationthat is sized and configured to receive a superior spinous process. Asseen in FIG. 3c , the anterior face of the superior extensions 14includes a slight concavity or curvature 45 for conforming to the bonyanatomy of the superior spinous process and or lamina. Extending betweeninferior extensions 44 a, 44 b is a strut, bridge, bracket or saddle 48that forms an inferior substantially U-shaped configuration that issized and configured to receive an inferior spinous process of a spinalmotion segment. As seen in FIG. 3f , the anterior face of the inferiorextensions 16 includes a slight convexity or curvature 47 for conformingto the bony anatomy of the inferior spinous process and/or lamina. Inone variation, the length of the saddle 46 of the superior arm 14 isapproximately 9.0 millimeters and the length of the saddle 48 of theinferior arm 16 is approximately 7.0 millimeters. Also, the tip-to-tipdistance of the superior extensions 42 a, 42 b is approximately 10.0millimeters and the tip-to-tip distance of the inferior extensions 44 a,44 b is approximately 9.0 millimeters. In sum, the seat comprising thesaddle 46 and superior extensions 42 a, 42 b formed by the superior arm14 is larger than the seat comprising the saddle 48 and inferiorextensions 44 a, 44 b formed by the inferior arm 16. The larger superiorseat of the spacer conforms closely to a wider lower end of the spinousprocess and the smaller inferior seat of the spacer conforms closely toa narrower upper end of the adjacent inferior spinous process when thespacer 10 is inserted between adjacent spinous processes as spinousprocesses are naturally narrower on top and wider on the bottom andthereby providing greater lateral stability to the spacer with respectto the spinous processes.

The superior and inferior arms 14, 16 are movably or rotatably connectedto the body 12, for example by hinge means or the like to providerotational movement from an undeployed configuration to a deployedconfiguration that arcs through about a 90 degree range or more withrespect to the body 12. The arms 14, 16 are rotationally movable betweenat least an undeployed, collapsed or folded state (as shown in FIGS.1a-1e ) and at least a fully deployed state (as shown in FIGS. 4 c, 5 cand 6 c). In the undeployed state, the arm pairs 14, 16 are alignedgenerally or substantially axially (i.e., axially with the longitudinalaxis defined by the body 12 or to the translation path into theinterspinous space of the patient) to provide a minimal lateral orradial profile. The longitudinal axis X of the spacer 10 and body 12 isshown in FIG. 1 c. In the deployed state, the arm pairs 14, 16 arepositioned generally or substantially transverse to the collapsedposition (i.e., transverse to the longitudinal axis defined by the body12 or to the translation path into the interspinous space of thepatient). In the deployed state, the arm pairs 14, 16 are positionedsuch that each of the U-shaped saddles are in a plane (or individualplanes) or have a substantially U-shaped projection in a plane that isgenerally or substantially transverse to the longitudinal axis X definedby the body 12 or to the collapsed position or to the implantation pathinto the interspinous space of the patient. In one variation, the spacer10 is configured such that the arms 14, 16 are linearly moveable ortranslatable within the same transverse plane from the deployed state(such as the state shown in FIGS. 4c, 5b and 6b ) to and from anadditionally extended state or second deployed state (such as the stateshown in FIGS. 4d, 5c and 6c ) characterized by an additionaltranslation of at least one of the arms 14, 16 with respect to the body12 along the direction of the arrows in FIGS. 4d and 6c away from ortowards the body 12. More specifically, the arms 14, 16 can be extendedin the general vertical or lateral direction along an axis along thegeneral length of the spine wherein the arms 14, 16 are extended awayfrom each other and away from the body 12 as denoted by the arrows inFIG. 4 d. The arms 14, 16 can be un-extended in a direction towards eachother and towards the body 12 for un-deployment or repositioning of thespacer 10 and shown by the arrows in FIG. 6c . This extended featureadvantageously allows for the most minimally invasive configuration forthe spacer without compromising the ability of the spacer 10 to seat andcontain the spinous processes or to laterally stabilize the spacerrelative to the spinous processes in between levels where the anatomy ofthe spinous processes is such that the interspinous process spaceincreases in the anterior direction of the patient or withoutcompromising the ability of the spacer to provide adequate distraction.The arms 14, 16 are connected to the body 12 and/or to each other in amanner that enables them to be moved simultaneously or independently ofeach other, as well as in a manner that provides passive deploymentand/or vertical extension or, alternatively, active or actuateddeployment and/or vertical extension.

Turning back to FIG. 1 f, the actuator assembly 18 will now bedescribed. The actuator assembly 18 includes an actuator 48, shaft 50and retainer 52. The actuator 48 includes a distal end 54 and a proximalend 56 and at least two bearing surfaces 58. The bearing surfaces 58angle towards each other from the proximal end 56 to the distal end 54.The proximal end 56 of the actuator 48 includes a shaft receivingportion 60 configured to receive the shaft 50. In one variation, theshaft 50 is integrally formed with the actuator 48. The distal end 54 ofthe actuator 48 is further configured to engage the superior andinferior arms 14, 16 such that forward translation of the actuator 48relative to the body 12 effects deployment of the arms into at least onedeployed configuration. The actuator assembly 18 is at least partiallydisposed inside the body 12 and is configured to move with respect tothe body 12.

Still referencing FIG. 1, the shaft 50 is substantially cylindrical inshape and includes a threaded outer surface for engagement with thethreaded inner surface of the actuator assembly receiving portion 26 ofthe body 12. The threads on the inner surface of the body 12 are formedby the conjunction of both left and right body pieces 20, 22. Theproximal end of the shaft 50 includes a hex socket 62 for receiving adriving tool. The distal end of the shaft 50 includes an actuatorengagement portion 64 configured to connect to the actuator 48. Theactuator engagement portion 64 as shown in FIG. 1 is a projection thatslides into a channel 66 on the actuator 48. Once inserted into thechannel 66, movement of the shaft 50 solely along the longitudinal axisof the spacer 10 will not release the shaft 50 from the actuator 48.

Still referencing FIG. 1, the retainer 52 is a circular ring preferablymade of metal such as steel or titanium. The retainer 52 fits into arecess 68 formed on the inner surface of the body 12. When pressed intothe recess 68, the retainer 52 secures the actuator 48 inside thepassageway 30 of the body 12.

Assembly of the spacer 10 with reference to FIGS. 1a-1f will now bedescribed. The arms 14, 16 are disposed in the arm receiving portion 24of one body piece. The other of the left or right body piece 20, 22 issecurely connected/welded to the one body piece thereby capturing thearms 14, 16 inside the arm receiving portion 24 such that the arms 14,16 are capable of at least rotational movement with respect to the body12 and in one variation, capable of rotational movement and translationwith respect to the body 12. The shaft 50 is connected to the actuator48 and together inserted and threadingly connected into the passageway30 of the body 12. The retainer 52 is passed over the proximal end ofthe shall 50 and snapped into the recess 68 of the body 12 to secure theactuator assembly 18 inside the body 12 such that the actuator assembly18 is capable of threaded translational movement with respect to thebody 12.

To deliver and deploy the spacer 10 within the patient, the spacer 10 isreleasably attached to a delivery instrument (not shown) at the proximalend of the spacer 10 via notches 34. The spacer 10 is provided orotherwise placed in its undeployed state as illustrated in FIG. 4a . Inthe undeployed state and attached to a delivery instrument, the spacer10 is inserted into a port or cannula which has been operativelypositioned in an interspinous space within a patient's back and theoutside of the patient via a minimally invasive incision. In somecircumstances it may not be necessary to use a cannula where the deviceis inserted through a larger opening in the skin. Where a cannula isemployed, the spacer 10 is then advanced through the cannula to withinthe targeted interspinous space between two adjacent spinous processes.The spacer 10 is advanced beyond the end of the cannula or,alternatively, the cannula is pulled proximately to uncover the spacer10 within. A driver such as a hex-shaped tool is inserted into the hexsocket 62 of the spacer 10 and turned to advance the shaft 50 of theactuator assembly 18. As the shaft 50 advances within the passageway 30,the bearing surfaces 58 of the actuator 48 contact the superior andinferior earning surfaces 41, 43 of the superior and inferior arms 14,16 forcing the arms 14, 16 to rotate about their pins 40 with respect tothe body 12. The arms 14, 16 rotate through an arc of approximately 90degrees into the deployed configuration in which the superior andinferior extensions 42 a, 42 b, 44 a, 44 b are substantiallyperpendicular to the longitudinal axis of the spacer 10 as shown inFIGS. 4c and 4d . In one variation, continued advancement of theactuator assembly 18 forces the arms 14, 16 outwardly in the directionof the arrows in FIG. 4d . Such outward translation is guided by thelength and shape of the slots 28. Once deployed, the superior arm 14seats the superior spinous process and the inferior arm 16 seats theadjacent inferior spinous process.

Retelling now to FIGS. 4a -4 d, the spacer 10 is shown in a closed,undeployed configuration (FIG. 4a ), a partially deployed configurationor otherwise intermediary configuration (FIG. 4b ), a deployedconfiguration (FIG. 4c ) and a deployed and extended configuration (FIG.4d ). In FIGS. 4a -4 d, the sagittal plane of the spacer 10 correspondsto the plane of the paper that bisects the spacer 10. In moving from anundeployed to a deployed configuration, the actuator assembly 18 and, inparticular, the shaft 50 of the actuator assembly moves distally withrespect to the body to a position flush or almost flush with theproximal end of the body 12 or to a position completely inside the body12 disappearing from sight providing a low profile for the spacer 10along the longitudinal axis of the body 12.

Turning now to the cross-sectional views of the spacer 10 in FIGS. 5a -5c, as the shaft 50 advances within the passageway 30, the bearingsurfaces 58 of the actuator 48 contact the superior and inferior earningsurfaces 41, 43 of the superior and inferior arms 14, 16 turning thearms 14, 16 into rotation with respect to the body 12. Upon rotation,the bearing surfaces 58 of the actuator 48 slide with respect to thesuperior and inferior caming surfaces 41, 43 of the superior andinferior arms 14, 16. The arms 14, 16 rotate through an arc ofapproximately 90 degrees with respect to the body 12 into the deployedconfiguration (FIG. 5b ) in which the superior and inferior extensionsof the arms 14, 16 are substantially perpendicular to the longitudinalaxis of the spacer 10 as shown in FIGS. 5b and with further actuationinto a deployed and extended configuration as shown in FIG, 5 c in whichthe arms 14, 16 have extended outwardly away from the body 12. The arms14, 16 have a substantially U-shaped projection in a plane perpendicularto the longitudinal axis of the spacer 10 or a substantially U-shapedprojection in a plane perpendicular to the longitudinal axis of thespacer 10.

Turning now to the semi-transparent views of the spacer 10 in FIGS. 6a-6 c, the rotation of the pins 40 of the arms 14, 16 in the openings 28of the body 12 is shown in moving from the configuration of FIG. 6a tothe configuration of FIG. 6 c. The translation of the pins 40 of thearms 14, 16 in the elongated portion of the slots 28 of the body 12 isshown in moving from the deployed configuration of FIG. 6b to thedeployed and extended configuration of FIG. 6c in the direction of thearrows in FIG. 6c . Such outward translation with respect to the body 12is guided by the length and shape of the slots 28. Reverse rotation ofthe spindle 86 moves the shaft 50 proximally with respect to the body 12allowing the arms to close to any intermediary configuration between adeployed, configuration and an undeployed, closed configuration. Thisfeature advantageously permits the surgeon to deploy and undeploy thespacer as needed to ease installation and positioning of the spacer withrespect to patient anatomy.

Any of the spacers disclosed herein are configured for implantationemploying minimally invasive techniques including through a smallpercutaneous incision and through the supraspinous ligament.Implantation through the supraspinous ligament involves selectivedissection of the supraspinous ligament in which the fibers of theligament are cut, separated or spread apart from each other in a mannerto maintain as much of the ligament intact as possible such as cutting,separating or spreading in a direction parallel to the orientation ofthe ligament fibers. This approach avoids crosswise dissection orcutting of the ligament and thereby reduces the healing time andminimizes the amount of instability to the affected spinal segment.While this approach is ideally suited to be performed through aposterior or midline incision, the approach may also be performedthrough one or more incisions made laterally of the spine with orwithout affect to the supraspinous ligament. Of course, the spacer mayalso be implanted in a lateral approach that circumvents thesupraspinous ligament altogether.

Other variations and features of the various mechanical spacers arecovered by the present invention. For example, a spacer may include onlya single arm which is configured to receive either the superior spinousprocess or the inferior spinous process or laterally stabilize the bodyof the spacer with respect to the superior spinous process and/or withrespect to the inferior spinous process. The surface of the spacer bodyopposite the side of the single arm may be contoured or otherwiseconfigured to engage the opposing spinous process wherein the spacer issized to be securely positioned in the interspinous space and providethe desired distraction of the spinous processes defining such space.The additional extension of the arm(s) subsequent to their initialdeployment in order to seat or to effect the desired distraction betweenthe vertebrae may be accomplished by expanding the body portion of thedevice instead of or in addition to extending the individual extensionmembers 14, 16.

The extension arms of the subject device may be configured to beselectively movable subsequent to implantation, either to a fixedposition prior to closure of the access site or otherwise enabled orallowed to move in response to normal spinal motion exerted on thedevice after deployment. The deployment angles of the extension arms mayrange from less than 90 degrees (relative to the longitudinal axisdefined by the device body) or may extend beyond 90 degrees. Eachextension member may be rotationally movable within a range that isdifferent from that of the other extension members. Additionally, theindividual superior and/or inferior extensions 42 a, 42 b, 44 a, 44 bmay be movable in any direction relative to the strut or bridgeextending between an arm pair or relative to the device body in order toprovide shock absorption and/or function as a motion limiter, or serveas a lateral adjustment particularly during lateral bending and axialrotation of the spine. The manner of attachment or affixation of theextensions to the arms may be selected so as to provide movement of theextensions that is passive or active or both. In one variation, thesaddle or distance between extensions 42 a and 42 b or between 44 a and44 b can be made wider to assist in seating the spinous process and thennarrowed to secure the spinous process positioned between extensions 42a and 42 b or between 44 a and 44 b. Spacers having different arm 14, 16configurations will now be discussed.

Turning now to FIGS. 7-11, there is shown another variation of thespacer 10 according to the present invention wherein like numerals areused to describe like parts. The spacer 10 of FIGS. 7-11 is adapted forimplantation into patients with adjacent spinous processes that aremisaligned such as patients with scoliosis where the spine curveslaterally forming an S-shaped or C-shaped curve. With reference to FIG.12, there is shown a scoliotic spine. Cobb's angle is a measurement usedfor evaluation of curves in scoliosis on an anterior-posteriorprojection of the spine as shown in FIG. 12. When assessing a curve ofthe spine, the apical vertebra is first identified. The apical vertebrais the most likely displaced and rotated vertebra with the least tiltedend plate. The end/transitional vertebra are then identified through thecurve above and below. The end vertebrae are the most superior andinferior vertebrae which are least displaced and rotated and have themaximally tilted end plate. As shown in FIG. 12, a line is drawn alongthe superior end plate of the superior end vertebra and a second linedrawn along the inferior end plate of the inferior end vertebra. If theend plates are indistinct the line may be drawn through the pedicles.The angle between these two lines (or lines drawn perpendicular to them)is measured as the Cobb angle. In S-shaped scoliosis where there are twocontiguous curves the lower end vertebra of the upper curve willrepresent the upper end vertebra of the lower curve. Because the Cobbangle reflects curvature only in a single plane and fails to account forvertebral rotation it may not accurately demonstrate the severity ofthree dimensional spinal deformity. Generally, a Cobb angle of 10 isregarded as a minimum angulation to define scoliosis. In a normal spinethe spinous processes of the spine are substantially aligned and lie inone plane, which for practical purposes will be defined as a sagittalplane. In particular, the projection of the spinous processes on acoronal plane will be substantially aligned with the sagittal plane. Ina scoliotic spine, the spinous processes are angle with respect to thesagittal plane. In particular, the anterior-posterior projection of thespinous processes on a coronal plane will show at least one spinousprocess angled with respect to the sagittal plane.

FIG. 7 shows an anterior-posterior view of a partially cross-sectionedsuperior spinous process 108 and an adjacent inferior spinous process110 between which the spacer 10 is implanted in a portion of a spineshowing a scoliotic curve C convex to the left. The spacer 10 of FIG. 7includes superior and inferior arms 14, 16 adapted to a scoliotic curveC that is convex to the left. The remaining components of the spacer 10such as the body 12 and actuator assembly 18 are similar if notidentical to the same components described above with respect to FIGS.1-6.

The superior and inferior arms 14, 16 include elongated superiorextensions 42 a, 42 b and elongated inferior extensions 44 a, 44 brespectively. Extensions 42 a and 44 a are located on the left andextensions 42 b and 44 b are located on the right. Superior extensions42 a, 42 b extend substantially parallel to each other in both anundeployed configuration and fully deployed configuration as do inferiorextensions 44 a, 44 b. As shown, extensions 42 a, 42 b, 44 a, 44 b aresubstantially parallel to the Y axis.

Extending between superior extensions 42 a, 42 b is a strut, bridge,bracket or saddle 46 that, together with superior extensions 42 a, 42 b,form a superior receiving portion or seat that is sized and configuredto laterally stabilize the body 12 with respect to the superior spinousprocess 108 and in one variation configured to receive at least aportion of a superior spinous process 108. In previous embodimentsdescribed above, when in the fully deployed configuration, the bridge 46is substantially perpendicular to the superior extensions 42 a, 42 b andsubstantially parallel to the X-Z plane where Z corresponds to thelongitudinal axis of the spacer 10 extending into and out of the page.In the embodiment shown in FIG. 7, the bridge 46 is angled with respectto the superior extensions 42 a, 42 b to adapt to the convex leftscoliotic curve C. The angled bridge 46 is integrally formed with thesuperior arm 14 or alternatively, the bridge 46 is a wedge-shaped insertadapted to modify a spacer 10 into a spacer 10 having an angled bridge46. The plane of the bridge 46 in the transverse or X-Y plane forms anangle θ with the Y-Z plane that is between 0 and 90 degrees, preferablybetween 5 and 60 degrees.

The Y-Z plane, where Z corresponds to the longitudinal axis of thespacer 10 extending into and out of the page, is the sagittal plane ofthe spacer 10 and it may or may not correspond to the sagittal plane ofthe patient's body or spine. FIG. 7 shows the superior spinous process108 and inferior spinous process 110 angled with respect to the sagittalplane with extensions 42 and 44 being substantially parallel to thesagittal plane.

Extending between inferior extensions 44 a, 44 b is a strut, bridge,bracket or saddle 48 that, together with inferior extensions 44 a, 441s,form an inferior receiving portion that is sized and configured tolaterally stabilize the body 12 with respect to the inferior spinousprocess 110 and in one variation configured to receive at least aportion of an adjacent inferior spinous process 110. In previousembodiments described above, when in the fully deployed configuration,the bridge 48 is substantially perpendicular to the inferior extensions44 a, 44 b and substantially parallel to the X-Z plane where Zcorresponds to the longitudinal axis of the spacer 10 extending into andout of the page. In the embodiment shown in FIG. 7, the bridge 48 isangled with respect to the inferior extensions 44 a, 44 b or angle withrespect to the sagittal plane to adapt to the convex left scolioticcurve C. The angled bridge 48 is integrally formed with the inferior arm16 or alternatively, the bridge 48 is a wedge-shaped insert adapted tomodify a spacer 10 into a spacer 10 having an angled bridge 48. Theplane of the bridge 48 in the transverse or X-Y plane forms an angle θwith the Y-Z plane or sagittal plane that is between 0 and 90 degrees,preferably between 5 and 60 degrees.

As shown in FIG. 7, the angled bridges 46, 48 conform the spacer 10 tothe scoliotic curve such that the superior and inferior spinousprocesses 108, 110 are seated in the superior and inferior arms 14, 16,or receiving portion of those arms, respectively, when in the deployedconfiguration. In another variation, the right superior extension 42 bis slightly shorter in length relative to the left superior extension 42a to better accommodate the angled superior spinous process in a convexleft scoliotic curve as shown in FIG. 7. Also, the right inferiorextension 44 b is slightly shorter in length relative to the leftinferior extension 44 a to better accommodate the angled inferiorspinous process in the convex left scoliotic curve. Furthermore, onlyone of the bridges 46,48 need be angled.

Turning now to. FIG. 8, there is shown another variation of the spacer10 according to the present invention wherein like numerals are used todescribe like parts. The spacer 10 of FIG. 8 is adapted for implantationinto patients with adjacent spinous processes that are misaligned suchas patients with scoliosis where the spine curves laterally forming anS-shaped or C-shaped curve. FIG. 8 shows a superior spinous process 108and an adjacent inferior spinous process 110 between which the spacer 10is implanted in a portion of a spine showing a scoliotic curve C convexto the right. The spacer 10 of FIG. 8 includes superior and inferiorarms 14, 16 configured to a scoliotic curve C that is convex to theright. The remaining components of the spacer 10 such as the body 12 andactuator assembly 18 of the spacer 10 are similar if not identical tothe same components described above with respect to FIGS. 1-6.

The superior and inferior arms 14, 16 include elongated superiorextensions 42 a, 42 b and elongated inferior extensions 44 a, 44 b,respectively. Extensions 42 a and 44 a are located on the left andextensions 42 b and 44 b are located on the right. Superior extensions42 a, 42 b extend substantially parallel to each other in both anundeployed configuration and fully deployed configuration as do inferiorextensions 44 a, 44 b.

Still referencing FIG. 8, extending between superior extensions 42 a, 42b is a strut, bridge, bracket or saddle 46 that, together with superiorextensions 42 a, 42 b, form a superior receiving portion that is sizedand configured to laterally stabilize the body 12 with respect to thesuperior spinous process 108 and in one variation receive a superiorspinous process 108. As shown, extensions 42 a, 42 b, 44 a, 44 b aresubstantially parallel to the Y-Z plane. In previous embodimentsdescribed above, the bridge 46 is substantially perpendicular to thesuperior extensions 42 a, 42 b and substantially parallel to the X-Zplane where Z corresponds to the longitudinal axis of the spacer 10extending into and out of the page. In the embodiment shown in FIG. 8the bridge 46 is angled with respect to the superior extensions 42 a, 42b to adapt to the convex right scoliotic curve C. The angled bridge 46is integrally formed with the superior arm 14 or alternatively, thebridge 46 is a wedge-shaped insert adapted to modify a spacer 10 into aspacer 10 having an angled bridge 46. The plane of the bridge 46 in thetransverse or X-Y plane forms an angle θ with the Y-Z plane or sagittalplane that is between 90 and 180 degrees, preferably between 120 and 175degrees.

Extending between inferior extensions 44 a, 44 b is a strut, bridge,bracket or saddle 48 that, together with inferior extensions 44 a, 44 b,form an inferior receiving portion that is sized and configured tolaterally stabilize the body 12 with respect to the inferior spinousprocess 110 and in one variation to receive an adjacent inferior spinousprocess 110. In previous embodiments described above, the bridge 48 issubstantially perpendicular to the inferior extensions 44 a, 44 b andsubstantially parallel to the X-Z plane where Z corresponds to thelongitudinal axis of the spacer 10 extending into and out of the page.In the embodiment shown in FIG. 8, the bridge 48 is angled with respectto the inferior extensions 44 a, 44 b to adapt the spacer 10 to theconvex right scoliotic curve C. The angled bridge 48 is integrallyformed with the inferior arm 16 or alternatively, the bridge 48 is awedge-shaped insert adapted to modify a spacer 10 into a spacer 10having an angled bridge 48. The plane of the bridge 48 in the transverseor X-Y plane forms an angle θ with the Y-Z plane that is between 90 and180 degrees, preferably between 120 and 175 degrees.

As shown in FIG. 8, the angled bridges 46, 48 conform to the scolioticcurve such that the superior and inferior spinous processes 108, 110 areseated in the superior and inferior arms 14, 16, respectively, when inthe deployed configuration. In another variation, the left superiorextension 42 a is slightly shorter in length relative to the rightsuperior extension 42 b to better accommodate the angled superiorspinous process in a convex right scoliotic curve as shown in FIG. 8.Also, the left inferior extension 44 a is slightly shorter in lengthrelative to the right inferior extension 44 b to better accommodate theangled inferior spinous process in a convex right scoliotic curve.

Turning now to FIG. 9, there is shown another variation of the spacer 10according to the present invention wherein like numerals are used todescribe like parts. The spacer 10 of FIG. 9 is adapted for implantationinto patients with adjacent spinous processes that are misaligned suchas patients with scoliosis where the spine curves laterally forming anS-shaped or C-shaped curve. FIG. 9 shows a superior spinous process 108and an adjacent inferior spinous process 110 between which the spacer 10is implanted in a portion of a spine showing a scoliotic curve C convexto the left. The spacer 10 of FIG, 9 includes superior and inferior arms14, 16 adapted to a scoliotic curve C that is convex to the left inwhich the superior and inferior arms 14, 15 are angled. The spacer 10may also be configured with superior and inferior arms 14, 16 adapted toa scoliotic curve C that is convex to the right in which the superiorand inferior arms, 14, 15 are angled in the opposite direction. Theremaining components such of the spacer 10 as the body 12 and actuatorassembly 18 of the spacer 10 are similar if not identical to the samecomponents described above with respect to FIGS. 1-6.

Still referencing FIG. 9, the superior and inferior arms 14, 16 includeelongated superior extensions 42 a, 42 b and elongated inferiorextensions 44 a, 44 b respectively. Extensions 42 a and 44 a are locatedon the left and extensions 42 b and 44 b are located on the right.Superior extensions 42 a, 42 b extend substantially parallel to eachother in both an undeployed configuration and fully deployedconfiguration as do inferior extensions 44 a, 44 b.

In the variation of FIG. 9, the superior extensions 42 a, 42 b areangled such that the superior extensions 42 a, 42 b form an angle θ withrespect to the Y-Z plane or sagittal plane when in the deployedconfiguration where Z corresponds to the longitudinal axis of the spacer10 extending into and out of the page. The angle θ is between 0 and 90degrees, preferably between 5 and 75 degrees. Likewise, inferiorextensions 44 a, 44 b are also angled such that the inferior extensions44 a, 44 b form an angle θ with the Y-Z plane when in the deployedconfiguration. The angle θ is between 0 and 90 degrees, preferablybetween 5 and 75 degrees. The superior arm 14 extensions 42 a, 42 b neednot have the same angle θ as the inferior arm 16 extensions 44 a, 44 b.

Still referencing FIG. 9, extending between superior extensions 42 a, 42b is a strut, bridge, bracket or saddle 46 that, together with superiorextensions 42 a, 42 b, form a superior receiving portion that is sizedand configured laterally stabilize the body 12 with respect to thesuperior spinous process 108 and in one variation to receive a superiorspinous process 108. The bridge 46 is substantially perpendicular to thesuperior extensions 42 a, 42 b. In the embodiment shown in FIG. 10, theplane of the bridge 46 in the X-Y plane is angled with respect to theX-Z plane or sagittal plane by the angle θ that is between 0 and 90degrees, preferably between 5 and 75 degrees to adapt to the scolioticcurve convex to the left.

Extending between inferior extensions 44 a, 44 b is a strut, bridge,bracket or saddle 48 that, together with inferior extensions 44 a, 44 b,form an inferior receiving portion that is sized and configured tolaterally stabilize the body 12 with respect to the inferior spinousprocess 110 and in one variation to receive an adjacent inferior spinousprocess 110. The bridge 48 is substantially perpendicular to theinferior extensions 44 a, 44 b. In the embodiment shown in FIG. 9, theplane of the bridge 48 in the X-Y plane is angled with respect to theX-Z plane by an angle θ that is between 0 and 90 degrees, preferablybetween 5 and 75 degrees to adapt to the scoliotic curve convex to theleft. As shown in FIG. 9, the angled bridges 46, 48 conform to thescoliotic curve such that the superior and inferior spinous processes108, 110 are received in the superior and inferior arms 14, 16,respectively, when in the deployed configuration.

Turning now to FIGS. 10 and 11, there is shown a partialanterior-posterior view of a spacer 10 illustrating a portion of thebody 12 and an inferior arm 16. The spacer 10 of FIG. 10 includes atleast one arm that articulates in the direction of the arrows toaccommodate a convex right or convex left scoliotic curve of varyingdegrees. Only the inferior arm is shown in FIGS. 10 and 11. The angle θthat the bridge 48 in the X-Y plane makes with respect to the Y-Z planeor sagittal plane where Z corresponds to the longitudinal axis of thespacer 10 extending into and out of the page is adjusted and locked by adriving tool 112 shown in FIG. 11 and configured to angulate thesuperior arm 14 and/or inferior arm 16 as desired so that the superiorarm 14 seats the superior spinous 108 process and the inferior arm 16seats the inferior spinous process 110.

The spacer 10 of FIGS. 7-11 are delivered and deployed within thepatient in the same manner as described above with respect to FIGS. 1-6.The spacers 10 of FIGS. 9-11 that are angled before delivery into thepatient require the clinician to angle the spacer 10 during deliveryinto the interspinous space. For example, when in the undeployedconfiguration, spacer 10 of FIG. 9 or the spacer 10 of FIGS. 10 and 11that is angled before delivery, requires insertion first along a pathparallel to the superior and inferior extensions 42 a, 42 b, 44 a, 44 b.The spacer 10 is then turned such that the body 12 trailing theextensions is oriented parallel to the same path so that the extensionsconform to the scoliotic curvature. Otherwise, the delivery anddeployment of the spacer 10 proceeds as described herein.

The spacer 10 is provided or otherwise placed in its undeployed, closedstate in juxtaposition to the insertion instrument 80 and connectedthereto as shown in FIG. 13a . The longitudinal axis of the insertioninstrument 80 is advantageously aligned with the longitudinal axis ofthe spacer 10 as shown. The delivery instrument 80 includes a firstsubassembly 102 to releasably clamp to the body 12 of the spacer 10 at adistal end of the insertion instrument 80. The first subassembly 102includes an inner clamp shaft (not shown) having flexible prongs 126 atthe distal end configured for attachment to the body 12 of the spacer 10and, in particular, for insertion into the notches 34 of the spacer body12. The first subassembly 102 includes an outer shaft 112 located overthe inner clamp shaft and configured for relative motion with respect toone another via a control 114 located at the handle assembly 106. Thecontrol 114 is threaded to the outer shaft 112 such that rotation of thecontrol 114 moves the outer shaft 112 along the longitudinal axis of theinsertion instrument 80 over the inner clamp shaft to deflect andundeflect the prongs 126 to connect or disconnect the instrument 80 toor from the body 12. The first control 114 is activated at the handle ofthe insertion instrument 80 such that the first subassembly 102 isconnected to the body 12 of the spacer 10. The first control 114 isrotated in one direction to advance the outer shaft 112 over the innerclamp shaft (not shown) deflecting the prongs 126 inwardly into thenotches 34 on the body 12 of the spacer 10 to secure the spacer body 12to the instrument as shown in FIG. 13a . Reverse rotation of the control114 reverses the direction of translation of the outer shaft 112 torelease the prongs 126 from the notches 34 and, thereby, release thespacer 10 from the instrument 80.

Still referencing FIG. 13a , the insertion instrument 80 includes asecond subassembly 104 that is configured to connect to the actuatorassembly 18 of the spacer 10. In particular, the second subassembly 104includes means located at the distal end of the second subassembly 104to activate the actuator assembly 18. In one variation, the secondsubassembly 104 is a pronged driver having an elongated shaft that isconfigured to be insertable into the notches of a spindle. In anothervariation, the second subassembly 104 is an elongated shaft withhexagonally-shaped tip configured to be insertable into a correspondinghexagonally shaped socket 62 of the shaft 50. The second subassembly 104is insertable at the proximal end of the instrument 80 and extendsthrough the handle assembly 106 and through the inner. The removabledriver 104 is rotatable with respect to the instrument 80 to rotate theshaft 50 and arrange the spacer 10 to and from deployed and undeployedconfigurations.

To deliver and deploy the spacer 10 within the patient, the spacer 10 isreleasably attached to a delivery instrument 80 at the proximal end ofthe spacer 10 as shown in FIG. 13 a. A small midline orlateral-to-midline incision is made in the patient forminimally-invasive percutaneous delivery. In one variation, thesupraspinous ligament is avoided. In another variation, the supraspinousligament is split longitudinally along the direction of the tissuefibers to create an opening for the instrument. Dilators may be furtheremployed to create the opening. In the undeployed state with the arms14, 16 in a closed orientation and attached to a delivery instrument 80,the spacer 10 is inserted into a port or cannula, if one is employed,which has been operatively positioned to an interspinous space within apatient's back and the spacer is passed through the cannula to theinterspinous space between two adjacent vertebral bodies. The spacer 10is advanced beyond the end of the cannula or, alternatively, the cannulais pulled proximately to uncover the spacer 10 connected to theinstrument 80. Once in position, the second assembly 104 is insertedinto the instrument 80 if not previously inserted to engage the actuatorand is rotated to rotate the shaft 50. The rotating shaft 50 advancesthe actuator 48 to begin deployment the spacer 10. Rotation in onedirection, clockwise, for example, threadingly advances the shaft 50which then results in the actuator 48 contacting the superior andinferior canting surfaces 41, 43 of the superior and inferior arms 14,16 to begin their deployment. FIG. 13b illustrates the superior arm 14and the inferior arm 16 in a partially deployed position with the arms14, 16 rotated away from the longitudinal axis. The position of the arms14, 16 in FIG. 13b may be considered to be one of many partiallydeployed configurations or intermediary configurations that are possibleand from which the deployment of the arms 14, 16 is reversible withopposite rotation of the second assembly 104. With further advancement,the arms 14, 16 rotate through an arc of approximately 90 degrees intothe deployed configuration in which the superior and inferior extensionsare substantially perpendicular to the longitudinal axis of the spacer10 as shown in FIG. 13 c.

Turning to FIG. 13c , there is shown an insertion instrument 80connected to a spacer 10 in a first deployed configuration in which thearms 14, 16 are approximately 90 degrees perpendicular to thelongitudinal axis or perpendicular to the initial undeployedconfiguration. Continued rotation of second assembly 104 rotates theshaft 50 further distally with respect to the body 12 of the spacer 10pushing the bearing surfaces 58 further against the superior andinferior camming surfaces 41, 43. While in the first deployedconfiguration of FIG. 13c , the clinician can observe with fluoroscopythe positioning of the spacer 10 inside the patient and then choose toreposition the spacer 101f desired. Repositioning of the spacer 10 mayinvolve undeploying the arms 14, 16 by rotating the shaft 50 via thesecond assembly 104 to rotate the arms into any one of the manyundeployed configurations and then moving the delivery instrument whileconnected to the spacer into a new position. The spacer wings may thenbe re-deployed into the desired location. This process can be repeatedas necessary with or without undeployment of the wings until theclinician has achieved the desired positioning of the spacer in thepatient. Of course, inspection of the spacer 10 may be made viafluoroscopy while the spacer 10 is in an intermediate or partiallydeployed configuration such as that of FIG. 13 b.

Even further advancement of the actuator shaft 50 via rotation of thesecond subassembly 104 from the first deployed configuration results inthe spacer 10 assuming a second deployed configuration shown in FIG. 13d, if the spacer 10 is so configured as to allow a second deployedconfiguration. The second deployed configuration is an extendedconfiguration as described above in which the superior and inferior arms14, 16 extend transversely with respect to the longitudinal axisoutwardly in the direction of the arrows in FIG. 4d . The spacer 10 isconfigured such that the outward translation of the arms 14, 16 followsthe rotation into 90 degrees and is guided by the length and shape ofthe openings 28 in which the arms 14, 16 move. Once deployed, thesuperior arm 14 seats the superior spinous process and the inferior arm16 seats the adjacent inferior spinous process. Such extension may alsoprovide some distraction of the vertebral bodies.

Following deployment, the second assembly 104 may be removed. Control114 is rotated in the opposite direction to release the body 12 from theinstrument 80. The insertion instrument 80, thus released from thespacer 10, is removed from the patient leaving the spacer 10 implantedin the interspinous process space as shown in FIG. 14. In FIG. 14, thespacer 10 is shown with the superior arm 14 seating the superior spinousprocess 138 of a first vertebral body 142 and the inferior arm 16seating the inferior spinous process 140 of an adjacent second vertebralbody 144 providing sufficient distraction to open the neural foramen 146to relieve pain. As mentioned above, the shape of the superior arm 14 issuch that a superior concavity or curvature 45 is provided to conform tothe widening of the superior spinous process 138 in an anteriordirection of the patient toward the superior lamina 148 going in theanterior direction. In general, the superior arm 14 is shaped to conformto anatomy in the location in which it is seated. Likewise, as mentionedabove, the shape of the inferior arm 16 is such that an inferiorconvexity or curvature 47 is provided to conform to the widening of theinferior spinous process 140 in an anterior direction toward theinferior lamina 150. The supraspinous ligament 152 is also shown in FIG.14. In FIG. 14, the lateral direction is into and out of the page andthe superior 14 and inferior arms 14, 16 are configured to laterallystabilize the spacer 10 with respect to the adjacent spinous processes138, 140.

The spacer 10 is as easily and quickly removed from body of the patientas it is installed. The instrument 80 is inserted into an incision andreconnected to the spacer 10. The shaft 50 is rotated in the oppositedirection via a driver 104 to fold the arms 14, 16 into a closed orundeployed configuration. In the undeployed configuration, the spacer 10can be removed from the patient along with the instrument 80 or, ofcourse, re-adjusted and re-positioned and then re-deployed as neededwith the benefit of minimal invasiveness to the patient.

Any of the spacers disclosed herein are configured for implantationemploying minimally invasive techniques including through a smallpercutaneous incision and through the supraspinous ligament.Implantation through the supraspinous ligament involves selectivedissection of the supraspinous ligament in which the fibers of theligament are separated or spread apart from each other in a manner tomaintain as much of the ligament intact as possible. This approachavoids crosswise dissection or cutting of the ligament and therebyreduces the healing time and minimizes the amount of instability to theaffected spinal segment. While this approach is ideally suited to beperformed through a posterior or midline incision, the approach may alsobe performed through one or more incisions made laterally of the spinewith or without affect to the supraspinous ligament. Of course, thespacer may also be implanted in a lateral approach that circumvents thesupraspinous ligament altogether as well as in open or mini-openprocedures.

All publications mentioned herein are incorporated herein by referenceto disclose and describe the methods and/or materials in connection withwhich the publications are cited. The publications discussed herein areprovided solely for their disclosure prior to the filing date of thepresent application. Nothing herein is to be construed as an admissionthat the present invention is not entitled to antedate such publicationby virtue of prior invention. Further, the dates of publication providedmay be different from the actual publication dates which may need to beindependently confirmed.

The preceding merely illustrates the principles of the invention. Itwill be appreciated that those skilled in the art will be able to devisevarious arrangements which, although not explicitly described or shownherein, embody the principles of the invention and are included withinits spirit and scope. Furthermore, all examples and conditional languagerecited herein are principally intended to aid the reader inunderstanding the principles of the invention and the conceptscontributed by the inventors to furthering the art, and are to beconstrued as being without limitation to such specifically recitedexamples and conditions. Moreover, all statements herein recitingprinciples, aspects, and embodiments of the invention as well asspecific examples thereof, are intended to encompass both structural andfunctional equivalents thereof. Additionally, it is intended that suchequivalents include both currently known equivalents and equivalentsdeveloped in the future, i.e., any elements developed that perform thesame function, regardless of structure. The scope of the presentinvention, therefore, is not intended to be limited to the exemplaryembodiments shown and described herein. Rather, the scope and spirit ofpresent invention is embodied by the appended claims.

We claim:
 1. An implant for placement between adjacent spinous processesin a spinal motion segment, the implant comprising: a body defining alongitudinal axis; a first arm connected to the body and configured tolaterally stabilize the body with respect to a first spinous processwhen in a deployed configuration; and a second arm connected to the bodyand configured to laterally stabilize the body with respect to a secondspinous process when in a deployed configuration; and wherein the firstand second arms are configured for placement between adjacent spinousprocesses in which at least one of the adjacent spinous processes has aprojection in a coronal plane that is angled with respect to thesagittal plane.
 2. The implant of claim 1 wherein the first arm includesa pair of first extensions configured to receive the first spinousprocess between the first extensions.
 3. The implant of claim 2 whereinat least one extension of the pair of first extensions is angled withrespect to the sagittal plane of the spacer.
 4. The implant of claim 2further including a first bridge connected between the first extensionsto define a first spinous process receiving portion.
 5. The implant ofclaim 4 wherein the first pair of extensions are substantially parallelto the sagittal plane of the spacer and the first bridge is angled withrespect to the sagittal plane of the spacer.
 6. The implant of claim 4wherein the first pair of extensions and bridge are angled with respectto the sagittal plane of the spacer.
 7. The implant of claim 6 whereinthe first bridge is substantially perpendicular to the first pair ofextensions.
 8. The implant of claim 2 wherein the second arm includes apair of second extensions configured to receive the second spinousprocess between the second extensions.
 9. The implant of claim 8 furtherincluding a first bridge connected between the first pair of extensionsto define a first spinous process receiving portion and a second bridgeconnected between the second pair of extensions to define a secondspinous process receiving portion.
 10. The implant of claim 9 whereinthe pair of first extensions and the pair of second extensions aresubstantially parallel to the sagittal plane of the spacer and the firstand second bridges are angled with respect to the sagittal plane of thespacer.
 11. The implant of claim 10 wherein the first and second bridgesare angled with respect to each other.
 12. The implant of claim 8wherein the pair of first extensions is angled with respect to thesagittal plane of the spacer and the pair of second extensions is angledwith respect to the sagittal plane of the spacer.
 13. The implant ofclaim 9 wherein the pair of first extensions is angled with respect tothe sagittal plane of the spacer and the pair of second extensions isangled with respect to the sagittal plane of the spacer and the firstand second bridges are perpendicular to their respective extensions towhich they are connected.
 14. An implant for placement between adjacentspinous processes in a spinal motion segment comprising; a body defininga longitudinal axis; a first arm connected to the body; the first armhaving a first pair of extensions defining a spinous process receivingportion for seating a superior spinous process therein; and a second armconnected to the body; the second arm having a second pair of extensionsdefining a spinous process receiving portion for seating an inferiorspinous process therein; wherein the distance between the first pair ofextensions is greater than the distance between the second pair ofextensions.
 15. The implant of claim 14 wherein the first pair ofextensions are substantially parallel and the second pair of extensionsare substantially parallel.
 16. The implant of claim 15 wherein thefirst pair of extensions is angled with respect to the second pair ofextensions.
 17. An implant for placement between adjacent spinousprocesses in a spinal motion segment comprising: a body defining alongitudinal axis; a first arm connected to the body; the first armhaving a first pair of extensions defining a spinous process receivingportion for seating a superior spinous process therein; and a second armconnected to the body; the second arm having a second pair of extensionsdefining a spinous process receiving portion for seating an inferiorspinous process therein; wherein one extension of the first pair and oneextension of the second pair that are adjacent to each other on the sameside of the spacer are both shorter than the other of the extensions.18. The implant of claim 17 further including a first bridge between thefirst pair of extensions and second bridge between the second pair ofextensions.
 19. The implant of claim 18 wherein the first and secondbridge are angled with respect to each other.
 20. The implant of claim17 wherein the first and second arms are angled with respect to eachother such that the shorter extensions are angled towards each other.21. The implant of claim 20 wherein the first pair of extensions areparallel to one another and the second pair of extensions are parallelto one another.
 22. An implant configured for placement between adjacentspinous processes in a spinal motion segment with a scoliotic curve andconfigured to laterally stabilize the spacer with respect to saidadjacent spinous processes.